1. Field of the Invention
The present invention relates to a spill containment device for the fill tubes of underground storage tanks, particularly tanks for environmentally hazardous liquids such as gasoline and other petroleum products.
2. Prior Art
U.S. Pat. No. 4,762,440 of the present invention shows various forms of an in-ground spill containment device usable to prevent spilled liquids, such as gasoline, from draining or seeping into the ground to possibly contaminate the soil and/or water supply. The device comprises a container that supports and surrounds one or more fill tubes (pipes) that extend downward to an underground liquid fuel storage tank so that fuel spilled during or after the tank-filling process is trapped in the container and does not migrate through the ground. A manually-operated valve in the bottom wall of the container drains the spilled liquid fuel through an auxiliary drain line into the tank, whereby fuel is prevented from accumulating in the container. To prevent rainwater from entering the container and mixing with liquid fuel, a removable cover is provided over the access opening at the top of the container. An edge of the cover seats in a water drain channel that surrounds the access opening, whereby surface water is trapped within the drain channel instead of possibly running down into the container. At least one drain conduit leads from the drain channel into the ground or onto the adjoining ground surface for draining water out of the channel.
The '440 patent shows various configurations the spill containment device can take. One structural arrangement comprises two separate fill pipes extending upwardly within a single rectangular container, each fill pipe extending downwardly to a different underground fuel storage tank.
The rectangular container is disposed within a surrounding cylindrical casing which spaces the container from the surrounding earth, thereby protecting the container from deformation or damage from the earth shifting or possibly corroding the container material. The cylindrical casing has a relatively heavy metal cover substantially flush with the ground or concrete surface. Two lighter covers are disposed over separate access openings in the spill containment container above the respective fill pipes. The individual covers may be removed individually, depending on which fill pipe is being used in a particular instance.
In another configuration shown in the '440 patent, the spill container comprises a cylindrical container embedded in a concrete slab that has its upper surface flush with the ground surface or concrete pavement surface. A single fill tube extends upwardly through the bottom wall of the cylindrical container for access through a top opening in the container body. The rim of the container forms a drain channel that intercepts surface water that might otherwise flow into the container.